1. Field of the Invention
The present invention relates to a transceiver module, and more particularly to an easily assembled optoelectronic transceiver module with high yield rate.
2. Description of the Prior Art
An optoelectronic transceiver module is used to transform an optical signal coming from an optical fiber connector to an electrical signal, or transform an electrical signal to an optical signal. A photo diode contained by the optoelectronic transceiver transforms the optical signal to the electrical signal and then sends the electrical signal to a processing circuit. A laser diode contained by the optoelectronic transceiver transforms the electrical signal coming from the processing circuit to the optical signal and then outputs.
As shown in FIG. 1(a), the conventional single mode transceiver includes a lower housing 10, an upper housing 20, a laser diode subassembly 30, a photo diode subassembly 60, a board 70 and a clamp 80. The laser diode subassembly 30 and the photo diode subassembly 60 are mounted on the board 70. The lower housing 10 is used to accommodate the laser diode subassembly 30 and the photo diode subassembly 60 and support the board 70. The lower housing 10 further includes two grooves 15 formed in one terminal of the lower housing. Each groove 15 has a semi-circular portion used to fix the laser diode subassembly 30 and the photo diode subassembly 60. Besides, the laser diode subassembly 30 and the photo diode subassembly 60 pass through the holes of the clamp 80. In this manner, the laser diode subassembly 30 and the photo diode subassembly 60 are optically coupled and connected with an optical fiber connector (not shown).
As shown in the assembling flowchart of the laser diode subassembly 30 illustrated in the FIG. 1(b), the laser diode subassembly 30 consists of a laser diode pack 40 and a sleeve 50. Among these, for the single mode transceiver, the sleeve 50 is composed of an upper sleeve 51 and a lower sleeve 53. In addition, the upper sleeve 51 has an upper flange 52 and the lower sleeve 53 has a lower flange 55. In general, the radius of the lower flange 55 is larger than the radius of the upper flange 52. The radius of the lower flange 55 is substantially the same with the radius of the semi-circular portion of the groove 15.
Referring to FIG. 1(a)-FIG. 1(c), for the single mode transceiver, the core of the single mode optical fiber has a radius of 9 xcexcm. Hence, it is strict with the requirement for the alignment of the optical. The optical axis of the laser diode pack 40 has to be aligned to the single mode optical fiber accurately. For this purpose, the cap 41 (e.g. To-can) of the laser diode pack 40 is plugged into the lower sleeve 53 through the terminal opposite to the lower flange 55 of the lower sleeve during assembling. Then, the lower flange 55 of the resultant structure is connected with the upper flange 52 of the upper sleeve 51 using laser-welding method.
During the laser-welding process, an optical fiber (not shown) and a testing device (not shown) are connected with the terminal opposite to the upper flange 52 of the upper sleeve 51. Besides, the lower sleeve 53 slightly moves on the interface between the lower flange 55 and the upper flange 52. Meanwhile, the testing device measures the optical coupling efficiency of the laser beam, emitting from the laser diode pack 40, respective to the optical fiber. Once the lower sleeve 53 moves to a position relative to the upper sleeve 51 and thus the optimum optical coupling efficiency is available for the testing device, a laser-welding apparatus forms several welding joints on the interface between the lower flange 55 and the upper flange 52. In this manner, the upper sleeve 51 is connected with the lower sleeve 53.
However, prior art encountered great difficulties in aligning the optical axis of the laser diode pack 40 to the central axis 56 of the lower sleeve 53 due to numerous reasons. As a result, the central axis 56 of the lower sleeve 53 fails to be aligned with the central axis 57 of the upper sleeve 51. For example, as shown in FIG. 1(b), the central axis 57 of the upper sleeve 51 is above the central axis 56 of the lower sleeve 53. Under these conditions, the laser diode pack 40 cannot be positioned in the lower housing 10 and cannot be fixed in the groove 15. This causes the lower housing 10 and the upper housing 20 to fail in tight fit. As shown in FIG. 1(c), this is because the height of resultant structure consisting of the lower sleeve 53 and the lower flange 55 exceeds the tolerance T provided by the lower housing 10 and the upper housing 20. As a result, the transceiver fails to be assembled and which leads to lower yield rate. The laser diode subassembly 30 is thus scrapped or reworked, and the manufacturing cost of the conventional transceiver is raised due to the lower yield rate.
Accordingly, there is a strongly felt need for an easily assembled optoelectronic transceiver module with high yield rate.
Consideration of the disadvantages of the conventional transceiver module described above, the main object of the present invention is to provide an easily assembled optoelectronic transceiver module with high yield rate.
The present transceiver module is coupled to a single mode optical fiber. The transceiver module includes a lower housing, a board, a transmitting subassembly, a receiving subassembly, a lower housing, and a clamp. The lower housing further includes at least one groove provided at one terminal of the lower housing. The groove is used to fix the transmitting subassembly and the receiving subassembly. The transmitting subassembly may be a laser diode subassembly and is used to emit laser beam. The receiving subassembly may be a photo diode subassembly and is used to accept the optical signal from the optical fiber coupled to the transceiver module. The received optical signal is sent to the board. The board is formed on the lower housing and electrically coupled to the transmitting subassembly and the receiving subassembly. Besides, there are other electrical devices, processing the optical signal, formed on the board. However, they are not illustrated since they are not features of the present invention.
The transmitting subassembly is formed in the lower housing and electrically coupled to the board. It should be noted that the transmitting subassembly further includes a laser diode pack, an upper sleeve and a lower sleeve. Among these, the laser diode pack emits laser beam. The upper sleeve includes a flange formed at a middle of the upper sleeve. The radius of the flange is substantially the same with the radius of the groove described above. Therefore, the groove can fix the flange. In addition, the respective terminal of the transmitting subassembly and the receiving subassembly passes through the preformed holes of the clamp. The clamp is used to clamp an optical fiber connector and make the transmitting subassembly and the receiving subassembly be coupled to the optical fiber.
The cap of the laser diode pack is plugged into one terminal of the lower sleeve. Then, the laser diode pack is connected with the upper sleeve via another terminal of the lower sleeve. For example, the upper sleeve is connected with the lower sleeve using laser-welding method. When the relative position of the upper sleeve and the lower sleeve can make a measuring device obtain the optimum optical coupling efficiency, the laser-welding apparatus forms several welding joints on the joint interface between the upper sleeve and the lower sleeve.
The receiving subassembly is positioned in the lower housing and electrically coupled to the board. The receiving subassembly responds to the optical signal of the optical fiber. The upper housing combined with the lower housing encapsulates the board, the transmitting subassembly and the receiving subassembly.
According to the present invention, the transmitting subassembly includes merely a single flange. Thus, the resultant structure composed of the laser diode pack and the lower sleeve does not interfere with the tight fit of the lower housing and the upper housing, even though the upper sleeve is misaligned to the lower sleeve. This is because the malposition (e.g. the joint interface between the upper sleeve and the lower sleeve) is shifted to the interior of the lower housing. The interior of the lower housing has adequate space to accommodate the transmitting subassembly with malposition. Therefore, the present transceiver has increased yield rate and is easily assembled.